Fuel cell vehicle

Abstract

A fuel cell vehicle comprises a motor , a fuel cell , a first DC/DC converter, and a first converter control unit . The first DC/DC converter performs a boosting operation when the fuel cell vehicle runs in a non-stationary state, and does not perform the boosting operation during the vehicle runs in a stationary state.

1. A method of controlling a fuel cell vehicle comprising a traction motor, a fuel cell, a first DC/DC converter for stepping up an output voltage of the fuel cell and supplying the stepped-up voltage to the traction motor, an electric storage device, a second DC/DC converter disposed between the traction motor and the electric storage device, and a controller for controlling the supply of electric power to the traction motor, the method comprising the steps of:
 setting the output voltage of the fuel cell to be higher than a necessary voltage of the traction motor when the fuel cell vehicle is in a rated state in which the traction motor operates to produce an output smaller than a continuous rated output thereof, and setting the output voltage of the fuel cell to be lower than the necessary voltage of the traction motor when the fuel cell vehicle is in a non-rated state in which the traction motor operates to produce an output larger than the continuous rated output; 
 by the controller, controlling the first DC/DC converter to step up the output voltage of the fuel cell when the controller judges that the output voltage of the fuel cell is lower than the necessary voltage of the traction motor; 
 by the controller, performing a current target value control process for the second DC/DC converter in the rated state; and 
 by the controller, performing a voltage target value control process for the second DC/DC converter in the non-rated state, 
 wherein the continuous rated output represents a rated guaranteed output as an output of the traction motor that is required for the fuel cell vehicle to climb a target gradient at a target vehicle speed which serves as a vehicle power performance target value; the rated state is a traction motor driving state for driving the traction motor at an output equal to or smaller than the rated guaranteed output; and the non-rated state is a traction motor driving state for driving the traction motor at an output greater than the rated guaranteed output. 
 
     
     
       2. A method of controlling a fuel cell vehicle according to  claim 1 , wherein the fuel cell vehicle further comprises: a bypass diode for supplying electric power from the fuel cell to the traction motor in bypassing relation to the first DC/DC converter. 
     
     
       3. A method of controlling a fuel cell vehicle according to  claim 1 , further comprising the steps of: by the controller, calculating a target current for the fuel cell; and by the controller, using the target current for the fuel cell as the current target value in the rated state and using the necessary voltage of the traction motor as the voltage target value in the non-rated state. 
     
     
       4. A method of controlling a fuel cell vehicle according to  claim 1 , wherein the fuel cell vehicle further comprises: a storage unit storing mapped data of requested outputs and necessary voltages of the traction motor. 
     
     
       5. A method of controlling a fuel cell vehicle according to  claim 1 , further comprising the step of: by the controller, comparing a target voltage for the fuel cell and the necessary voltage of the traction motor with each other, and determining whether the fuel cell vehicle is in the rated state or in the non-rated state, based on the result of the comparison. 
     
     
       6. A method of controlling a fuel cell vehicle comprising a traction motor, a fuel cell, a first DC/DC converter for stepping up an output voltage of the fuel cell and supplying the stepped-up voltage to the traction motor, an electric storage device, a second DC/DC converter disposed between the traction motor and the electric storage device, and a controller for controlling the supply of electric power to the traction motor, the method comprising the steps of:
 setting the output voltage of the fuel cell to be higher than a necessary voltage of the traction motor when the fuel cell vehicle is in a rated state in which the traction motor operates to produce an output smaller than a continuous rated output thereof, and setting the output voltage of the fuel cell to be lower than the necessary voltage of the traction motor when the fuel cell vehicle is in a non-rated state in which the traction motor operates to produce an output larger than the continuous rated output; 
 by the controller, controlling the first DC/DC converter to step up the output voltage of the fuel cell when the controller judges that the output voltage of the fuel cell is lower than the necessary voltage of the traction motor; 
 by the controller, constantly performing a voltage target value control process for the second DC/DC converter in either one of the rated state and the non-rated state; and 
 by the controller, using different voltage target values respectively in the rated state and the non-rated state, 
 wherein the continuous rated output represents a rated guaranteed output as an output of the traction motor that is required for the fuel cell vehicle to climb a target gradient at a target vehicle speed which serves as a vehicle power performance target value; the rated state is a traction motor driving state for driving the traction motor at an output equal to or smaller than the rated guaranteed output; and the non-rated state is a traction motor driving state for driving the traction motor at an output greater than the rated guaranteed output. 
 
     
     
       7. A method of controlling a fuel cell vehicle according to  claim 6 , wherein the fuel cell vehicle further comprises: a bypass diode for supplying electric power from the fuel cell to the traction motor in bypassing relation to the first DC/DC converter. 
     
     
       8. A method of controlling a fuel cell vehicle according to  claim 6 , further comprising the steps of: by the controller, calculating a target current for the fuel cell, and calculating a target voltage for the fuel cell from the target current; and by the controller, using the target voltage for the fuel cell as the voltage target value in the rated state and using the necessary voltage of the traction motor as the voltage target value in the non-rated state. 
     
     
       9. A method of controlling a fuel cell vehicle according to  claim 6 , wherein the fuel cell vehicle further comprises: a storage unit storing mapped data of requested outputs and necessary voltages of the traction motor. 
     
     
       10. A method of controlling a fuel cell vehicle according to  claim 6 , further comprising the step of: by the controller, comparing a target voltage for the fuel cell and the necessary voltage of the traction motor with each other, and determining whether the fuel cell vehicle is in the rated state or in the non-rated state, based on the result of the comparison. 
     
     
       11. A method of controlling a fuel cell vehicle comprising a traction motor, a fuel cell, a DC/DC converter for stepping up an output voltage of the fuel cell and supplying the stepped-up voltage to the traction motor, and a controller for controlling the supply of electric power to the traction motor, the method comprising the steps of:
 setting the output voltage of the fuel cell to be higher than a necessary voltage of the traction motor when the fuel cell vehicle is in a rated state in which the traction motor operates to produce an output smaller than a continuous rated output thereof, and setting the output voltage of the fuel cell to be lower than the necessary voltage of the traction motor when the fuel cell vehicle is in a non-rated state in which the traction motor operates to produce an output larger than the continuous rated output; and 
 by the controller, controlling the DC/DC converter to step up the output voltage of the fuel cell when the controller judges that the output voltage of the fuel cell is lower than the necessary voltage of the traction motor, 
 wherein the continuous rated output represents a rated guaranteed output as an output of the traction motor that is required for the fuel cell vehicle to climb a target gradient at a target vehicle speed which serves as a vehicle power performance target value; 
 the rated state is a traction motor driving state for driving the traction motor at an output equal to or smaller than the rated guaranteed output; and 
 the non-rated state is a traction motor driving state for driving the traction motor at an output greater than the rated guaranteed output.